This invention relates to a plaster for achieving percutaneous absorption of salbutamol.
Salbutamol [1-(4-hydroxy-3-hydroxymethylphenyl)-2-(tert-butylamino)ethanol] is a beta-adrenergic drug. It acts strongly on beta-two (.beta..sub.2) receptors on the bronchial muscle. It is used, generally in the form of sulfate, as a prophylactic agent for bronchial asthma, infantile asthma and the like or as a therapeutic agent for bronchitis and so forth.
In the prior art, this drug is administered to patients by the oral route in the form of tablets, syrups, inhalations (aerosols), etc.
However, oral administration of said drug has the following problems:
(1) Since the duration of the effect of salbutamol administration is generally about 6 hours, three or four administrations are required daily for the prevention of attacks. It is difficult to prevent asthmatic attacks while the patient is asleep or immediately after the patient's getting up early in the morning.
(2) It is difficult to administer the drug during an asthmatic attack.
(3) When the drug is absorbed through the digestive tract, the drug absorption may vary depending on the pH within the gastrointestinal tract and the extent of food intake. In addition, since the first-pass effect is great, an excessive dose may possibly cause palpitation, tachycardia, arrhythmia or blood pressure fluctuation due to sympathetic excitation or, furthermore, may possibly induce side effect, such as headache, dizziness, drowsiness, anorexia and nausea.